Sponsorships generate good will in the mind of the customer. Example, you sponsor Mo ... and some of us, myself included, go from "who's Tekin?" to thinking, "hmmm... maybe I need to get one of those...."
Does the money "trickle down" from big races? I think it does. Big races fuel little ones. Who plays football in the back yard, and doesn't dream of playing in the Super Bowl?
#3 (the best reason)
Although most companies today exist solely to make owners money, there's no reason the mission can't be "make enough cash to have a blast being race bums all over the US and the world". Actually I suspect most R/C companies fall close to this model ....
If you love R/C racing, by all means sponsor whatever you can. Big "Superbowl" races... local races that bring in the new racers and weekend warriors... drivers who show us in person that the stuff is good... cash is good, product is good, it all helps us be able to afford to race and put on races. We love racing
so we appreciate the help.